Telephone-receiver.



Patented mar. 27, I900. .A. K. KELLER.

IELEPHONE RECEIVER. .(App licg it i'pjhied Feb. 6, {899. xene' ed dct.11, 1599.

No Mm) ALBERT K. KELLER, or PHILADELPHIA, PENNSYLVAX PATENT @FFIQE A,ASSIGNOR TO THE INTERNATIONAL TELEPHONE AND SlVITCHBOARD MAXYFACTURINGCOMPANY, OF PLAINFIELD, NEW JERSEY.

TELEPHON-E RECElVER.

SPECIFICATION forming part of Letters Patent No. 645,959, dated March27,

Application filed February 6,1899. Renewed Oct To all whom it mayconcern:

Be it known that I, ABBERT K. KELLER, a citizen of the United States,residing in the city and countyof Philadelphia,State of Pen nsylvania,have invented'certain new and useful Improvements inTelephone-Receivers, of which the following is a specification,referencebeinghadto the accompanyingdrawings, forming a part hereof.

This invention has relation to the means for supporting the magnet of atelephone-receiver within its shell or casing One object of theinvention is to make the magnet easy of adjustment toward and from thediaphragm and at the same time to provide for fastening the magnetsecurely in position when it has been adjusted.

Another object is to guard against expan sion of the magnet-cores andconsequent loss of adjustment by the heat of the hand in handling theinstrument, as Well as to prevent the transmission of electric shocks tothe person handling the instrument.

In accordance with this invention the shell or casing of the receiver ismade wholly of rubber or other suitable non-conducting material and hasan interior space or chamber of sufficient size to receive the magnetwithout touching the same at any point. An internally-threaded sleeve issecurely fastened to or embedded in thetvall of the shell or casing,preferably near the end which receives the diaphragm, eneircling thecentral chamber and provided with an inwardly-projecting danger Anencircling collar secured to the magnet at a corresponding point isscrewthreaded to engage the interiorly-threaded sleeve or thimble abovereferred to and is provided near its-circumference with one or moreset-screws parallel to the axis and arranged to impinge upon the flangeof the sleeve or thimble, their heads being accessible from the open endof the shell when the diaphragm has been removed in the usual manner.When the magnet has been adjusted in position by ro tating it, with itscollar; within the interiorlythreaded sleeve or thimble, the set-screwsareturned until they bear upon the flange and so cause the collar tobind within the thim- -after indicated, is represented at A.

ober 11,1899. Serial No. 733,327. No model.)

ble and its further rotation to be prevented. The invention isillustrated in the accompanyingdrawings, in which Figure 1 is alongitudinal central section of the receiver constructed in accordancewith my invention. Fig; 2 is an end view of the same with the diaphragmand cap removed.

I Fig. 3 is adetail view, partly in section, of the sleeve secured to.the shell or casing. Fig. 4 shows in detail the threaded collar whichsupports the magnet, and Fig. 5 shows in detail the carrier-block forthe magnet.

In the construction represented in the drawin gs a shell or casing orholder of hard rubber or other suitable material and of usual orsuitable form and construction, except as herein- The diaphragm B isapplied to the enlarged end of the shell or holder and is secured inplace in the usual manner by the cap or cover 0. Within the shell orholder and encircling the central chamber thereof, preferably near theenlarged end, is an interiorly-threaded sleeve or thimble D, being heldsecurely in place many suitable manner, as by having the shell cast ormolded about it. This sleeve or thimble is also provided with aninwardly-turned flange diet a purpose presently to be described. The magnet E, of any usual or suitable form,'is supported by a ring carrier F,which is exteriorly threaded to engage the threaded sleeve or thimble D,so that by rotation. of the magnet,

with the carrier, within the sleeve or thimble the distance of the polesof the magnet from the diaphragm B can be adjusted. It is necessary thatthe parts he held firmly and securelyin their adjusted positions, andforthis purpose the ring carrier F is provided with one or more sot-screwsf parallel with the axis and arranged to bear upon the flange d of thesleeve or thimble D. The heads of these screws are readilyaccessible'when the diaphragm B and cap or cover 0 are removed, and bysetting them up after adjustment of the magnet until their pointsimpinge upon the flange d the carrier F is made to bind within the saidsleeve or-thimble and is securely held against further rotation ineither direction. For convenience in construction a clamping block orholder G is provided for insertion between the arms of the magnet E,being cut away, as at g, on opposite sides to receive the respectivearms of the magnet and having its sides curved in the arc of a circle tofit tightly within the carrier F. A bolt G may be passed through thearms of the magnet and through said block or holderto bind all'firmlytogether. 4

It will be observed that the magnet is out of contact with the shell orcasing A throughout its length and is supported near the diaphragm only,so that it is thoroughly insulated from the heat of the hand when thereceiver is in use, and its adjustment is therefore not likely to bealfected'. In the same manner, also, the person using the instrument isprotected from the transmission of electric shocks, there being no metalwhatever exposed for contact. The conneeiingwires are led through aholeformed for the purpose in the end of the shell or casing and areconnected directly with the wires of the magnet coils.

I claim as my invention 1. In a telephone-receiver, the combination witha shellor casing and a magnet, of asleeve or thimble secured to theshell or casing and encircling the central chamber, said sleeve or orthimble secured to the shell or casingapd encircling the centralchamber, said sleeiegtf thimble being interiorly threaded and havllg aninwardly-turned flange,'a'carrier forithe magnet exteriorly threaded toengage said, sleeve or thimble, set-screws in said carrier arranged toimpinge against said flange, and a clamping block or holder for themagnet slotted toreceive the arms of the magnet and formed to fittightly within said carrier, substantialig, as shown and described.

nis specification signed and witnessed this 17th day of January, A. D.1899.

ALBERT K. KELLER.

In presence of- ANTHONY N. JESBERA,

F M. EGGLESTQN.

